Taking a sequence of hits from a gravity bong(also known as a gb or "tube", hence the name.) This comes from the North Jersey dialect for taking a hit from a gravity bong as "ripping a tube." Therefore, ripping more than one tube in a row is called "surfing the net" because after all, the internet is really just a series of tubes.
A: Hey, are you ripping another? How many is that?
B: This'll be my second.
A: Oh snap, you'll be surfing the net soon.
B: Hold on, I have to log on.